var a = setInterval(function() {
	var b = document.querySelector('#b');
	var c = document.querySelector('#c');
	var d = document.querySelector('#d');
	
	
	var date1 = new Date();
	//获取之前的日期
	var date2 = new Date('2019/09/10 10:59:00');

	var date3 = date2 - date1;
	
	//小时
	var date4 = Math.floor(date3 / (1000 * 60 * 60));

	var date5 = date3 % (1000 * 60 * 60);

	//分钟
	var date6 = Math.floor(date5 / (1000 * 60));

	var date7 = date3 % (1000 * 60);
	
	//秒
	var date8 = Math.floor(date7 / (1000));
	
	b.innerHTML = date4;
	c.innerHTML = date6;
	d.innerHTML = date8;

})
